Unfortunately, I have not found in it any helpful information to identify a propeler I have.
It is a Chauviere wooden propeller (identified through a "Chauviere patent B.R.G.D" marking). It has been damaged (one tip of the two blades is broken).
The propeller is covered by a black varnish identified through a "Tonkilaque S.E.E.T." marking.
Main dimensions are :
- original diameter : 2.7 m
- hub thickness : 183 mm
- 8 holes of about 12 mm located on a 170 mm diameter
- hub housing = 80 mm
Following markings can also be identified on the propeller on the o.d. of the hub :
L.1 L5
Am 220
SERIF 24181
N° 66856 (on the hub o.d. but also on the face of the hub)
D1 sFA Gz

Would you please help me identifying on which engine/aircraft this propeller was installed ?

Your propeller dates from the end of 1918. It was made for the Letord L5 which is stamped on the hub as Let L5. It was primarily used as a long range photo reconnaisance aircraft.

The L4 used two Lorraine Dietrich engines of 160hp and the L5, mostly two LD engines of 240hp. Early versions used the LD engine of 220hp. I think that what looks like Am 220 is probably Lrra 220 or some similar abbreviation for Lorraine.

Tonkilaque is the trade mark of the company, Tonka, who produced the hard black lacquer which offered some protection. SELT refers, I think, to Societe E... Lacquer Tonka. Perhaps E indicates Eboniste. Perhaps our French forumites will advise us.

SFA is the airworthiness mark. The letters stand for La Service des Fabrications de l'Aviation

Serie 24181 is the drawing number which identifies the prop as made by Chauviere for a Letord with a Lorraine 220hp engine, diameter 2700mm and pitch 1880mm.

The most important stamping for identification is the SERIE 24181, which is a Chauviere series number and is listed as diameter 2.7, pitch 1.88, type "C", bore 80mm, all of which corresponds with your description.

According to a 1918 document I have from the AEF, that model was used on a Letord airplane with a Lorraine 220 HP engine. (An alternate propeller for that aircraft was a Eclair Series 84 of 2.75m). The Letord is the only aircraft that has that model number listed. I am confident that this is the correct identification.

Thanks to Stéphane for postings these pictures: it's ever a pleasure to have very detailed ones in attempting to understand propellers markings!

I think the abbreviation "Am" for the engine has an explanation there: http://www.hydroretro.net/etudegh/mo...onlorraine.pdf on pages 7 and 8 (in French ...). Gérard Hartmann explains that in 1915 Lorraine engine for militaries had the initial AM (for Aviation Militaire (Military Aviation)). The first one was a 110 HP vertical 6 cylinders, approved in March 1915 and named AM6A. In November, they made a 150 HP (at 1500 rpm) V8 on the same base, approved in January 1916. Then, at the beginning of 1917, the same engine was approved for 170 HP by increasing its rotation speed to 1650 rpm, and the same year appeared a new version ("Bc") by increasing stroke: at the same rpm (1650), it is 220 HP : there we are ! It explains the "Am 220" marking on the Chauvière. Probably, in military papers, it was an evolution of the same engine, so they keep the "AM" designation, even if Lorraine only named it 8Bc.

About the Tonkilaque S.E.L.T. sticker: I had seen it on French lacquered propellers in original condition of different brands: Ratier, Levasseur, Régy, Leseurre (see my post in modern propellers about this one) and perhaps others (it was a time I don't keep records ... Bad boy !)

As Bob said, Tonkilaque is the trademark. It is a word made with Tonki (from "Tonkin", the old name for northernmost part of Vietnam) and the French word "laque" (= lacquer), as the company was importing (or was supposed to) its lacquers and/or ingredients from there.

S.E.L.T. is probably the company name, for example Société d'Exploitation des Laques du Tonkin (= Company for Use of Tonkin Lacquers), but this is not sure: All lacquered Ratier propeller I have seen have this sticker, and all Ratier invoices or letters about lacquering are to the same address in Boulogne (just near Paris, not the harbor), 33 rue de Silly. However, on the invoices, the company name change:
Société des Laques d'Extrême-Orient (= Company for Far East Lacquers), in October 1921 and September 1921,
Société des Laques en Extrême-Orient (=Far East Company for Lacquers), in September 1922,
Société des Laques Indochinoises (= Company for Indochinese Lacquers), in December 1922.

It is not possible to make SELT with these names. Perhaps, it is an older one (I can't remember where I read "Société d'Exploitation des Laques du Tonkin"), and the company kept it on the stickers ? Or perhaps the writing on Ratier invoices is approximate ? I think a research in French 1920's aviation magazines could be done, but this a lot of work !

Remark : in "L'Ouvrier Moderne" (in English, "The Modern Worker") Tome VI n°1 (April 1923), there is an article about propeller construction. It is written that all French propellers are lacquered in the same factory: Société Française d'Expansion en Extrême-Orient (French Company for Expansion in Far East). Another time, there is no way to make "SELT" with this name ...

Best regards,
PM

Edit on 11/03 5:25 EU time: adding last remark and rectifying 150HP in 170HP somewhere in the text.

I found a 1919 book*** explaining the abbreviation SELT: SELT means Société d'Exploitation des Laques Tonkinoises (Something like "Company for Exploitation of Tonkinoise Lacquers" in English). It is a subsidiary of Société Française d'Expansion en Extrême-Orient (French Company for Expansion in Far-East). Main company had its office in Paris (19 rue d'Aumale) and lacquering shop was in Boulogne-sur-Seine (33 rue de Silly).

In the same book, we learn more (and there are four lacquering shop photos):
During 1917, experiments were conducted at Chalais-Meudon by French aeronautical laboratory, showing lacquer is more resistant than French varnish in use for propellers. In 1918, the company asked SFA (Service des Fabrications de l'Aviation) about a contract for 15000 propellers lacquering. It explains why Ratier (and probably others) sold its props to SFA without lacquering cost and those props were send to SELT for lacquering : SFA was paying separately for the props and for the lacquering.

It only remains for me to find trace of the filing of the trademark Tonkilaque at the INPI (French Institute where trademarks are registered). It will be easier as now year of deposit is known. I will rush there as soon as I will be in Paris !

*** De Brunoff, L'Aéronautique pendant la Guerre Mondiale, Paris, 1919, p. 725 and 726 (a well known book I forgot to search …).

About the Salmson A2A prop, I think it was made by Régy. The SFA decal is 99,99% chance from Service des Fabrications de l'Aviation. I have the same on a serial 15 n°19 Ratier prop billed to SFA on 27th November 1915:

Why SFA put his own decal on a prop made by somebody else? I think the prop has been re-varnished by them:
- there is no log of repairing or re-varnishing this very prop in Ratier books (I read hundreds of repairing logs, … but I might miss this one),
- and the Ratier trademark is varnished on this prop (and others we have aren't).
So, I think people who did it don't care varnishing Ratier trademark, and put theirs.

If you have access to the 2A2 prop, I think you will find a very very faint Régy stamp on the hub flat side, just at the beginning of one blade. Those are from a restored (…) prop at Le Bourget Musée de l'Air and from a Régy serial 300: